Ya'll know I've been rebuilding a classic telescope.
This last month I've been stripping and repainting all the external parts.
A line of bubbles appear at the outside edges of the metal.
It's not there when I 1st paint, or even a few hours later.
The next day, with the paint cured, I see these small bubbles on the edge.
all in a line along the outside edge.
Even with several coats, they still appear, even after sanding and cleaning.
It a gloss black paint, so I have to avoid over spray to get the gloss.
Am I over spraying? Is it a natural effect of the paint?

Most of the parts are cast Aluminum, some are high grade steel, but not stainless steal. No plastic at all. A few brass parts, that won't be painted, because they are in the gear drives.
I'm using a primer and paint all in one. Krylon Maxx.
The original primer is a blue alcohol, then a green undercoat, and then several coats of satin black. All of them lead based. that's why I used a chemical stripper, and an after wash.
The parts that don't have sharp outer edges, that are round or flat, look great!
Even inner edges look good.

sounds like you are getting a reaction possibly along a seem of some kind?
may be something in a solder reacting with your paint
you could try a high build catalyzed primer, you can ask the guy at your auto supply

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sounds like you are getting a reaction possibly along a seem of some kind?
may be something in a solder reacting with your paint
you could try a high build catalyzed primer, you can ask the guy at your auto supply

I've got 3 to 6 coats of paint on all the parts.
There is no solder on aluminum.
the canned spray paint is a combined primer and paint.
All the round part look great. It's only at a 90d edge.
Seems the paint piles up, but doesn't flow, to form a drip point, but still forms a line of bubbles along the edge.
All I can do is keep sanding down, and repainting.
Some of the parts will have 10 or more coats.

Is it on all surfaces with a 90 deg angle?
Try giving it a few dry coats using the same paint. Stand further away so that the paint has time to lose some liquid in the air before mating with the surface. It may need rubbing back to get an even finish after applying, but it usually stops interaction between the paint and the problem area.

Is it on all surfaces with a 90 deg angle?
Try giving it a few dry coats using the same paint. Stand further away so that the paint has time to lose some liquid in the air before mating with the surface. It may need rubbing back to get an even finish after applying, but it usually stops interaction between the paint and the problem area.

Not all the time. At 1st I thought I didn't get the parts cleaned properly.
But after MANY coats, the paint still does it, but not always in the same place. A nice little line of small bubbles right along a flat area at the edge. No dripping or flowing of the paint is evident - just the bubbles.

Thanks Dan, I hoped you would chime in on this.
I'm obviously not a good painter, and you know what your talking about.
I'll try your advice later today.

I get the polar and declination casings back from the shop Wednesday, and I'm trying to get everything painted before then. So by this coming weekend I can start assembling the scope.